Author: Salindi P. Herath
Herath, Salindi P., 2025 Influence of Mechanical Factors on Bone Remodelling in the Proximal Tibia Following a Primary Total Knee Arthroplasty, Flinders University, College of Science and Engineering
Terms of Use: This electronic version is (or will be) made publicly available by Flinders University in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. You may use this material for uses permitted under the Copyright Act 1968. If you are the owner of any included third party copyright material and/or you believe that any material has been made available without permission of the copyright owner please contact copyright@flinders.edu.au with the details.
Total knee arthroplasty (TKA) is an orthopaedic procedure that can relieve pain and improve function of the knee joint, primarily used to treat people with end-stage knee osteoarthritis (OA). One of the most common reasons for failure of a TKA worldwide is due to aseptic loosening of the tibial component, which can occur secondary to bone loss in the proximal tibia adjacent to the implant. Bone remodelling is influenced by physiology in addition to mechanical factors such as joint loading. The second chapter of this thesis is a systematic review and meta-analysis that synthesized the results of the literature that quantified bone remodelling following a primary TKA and investigated factors that influenced these changes. This review identified that no study had directly analysed the relationship between changes in joint loading and bone remodelling after surgery. Therefore, the central aim of this thesis was to characterize bone mineral density (BMD) changes in the proximal tibia using dual energy X-ray absorptiometry (DEXA) and investigate its relationship with mechanical factors, including knee joint reaction forces (JRF), following a primary TKA. To address this aim, an observational clinical trial was conducted which recruited twenty-two participants awaiting TKA to receive DEXA scans and complete motion capture preoperatively and up to 12-months following surgery.
In chapter 3 and chapter 4, a musculoskeletal modelling pipeline was designed to quantify changes in JRFs following TKA in people with knee OA. Chapter 3 developed a method for incorporating tibial and femoral sagittal plane mechanical axes into a generic model that led to joint load distributions that correlated with lower limb alignment. Chapter 4 quantified errors in spatial misalignment between external loads measured by force platforms and the model following inverse kinematics and determined that correction using the position of the ankle joint centre significantly affected estimations of external knee joint moments. In combination, these methods ensured accurate positioning of external loads with respect to the model and produced estimations of knee joint load distribution that varied with alignment deviations seen in people with knee OA reported in literature.
In chapter 5, JRFs were estimated using the previously developed musculoskeletal modelling workflow with an electromyography (EMG) informed estimation of muscle forces utilizing the Calibrated EMG-informed Neuromusculoskeletal Modelling (CEINMS) toolbox. A significant reduction in medial, lateral, and total joint loading was found in the first three months post-operation during level gait and a sit-to-stand activity. Between 6- and 12-months post-operation, a slight increase in knee JRFs was observed. However, medial, lateral, and total contact loads remained below preoperative levels at 12-months following surgery for both level gait and the sit-to-stand activity.
In chapter 6, BMD was measured in three areas, the medial and lateral condyles under the tibial baseplate and distally directly under the implant stem. BMD was measured in two subregions within each area of the proximal tibia, one closer to the implant and the second further distally. Regions closest to the implant experienced the largest change in BMD and this occurred primarily within the first three months post-operation. Bone loss occurred medially while an increase in BMD was observed laterally and distally. Multivariable linear regression results further revealed preoperative bone density as a significant negative explanatory variable for postoperative changes in BMD.
Chapter 7 investigated the relationship between bone remodelling and preoperative BMD, lower limb alignment, tibial component size, and JRFs. Multivariable linear regression retained preoperative BMD as a significant negative explanatory variable of bone remodelling across all three areas of the proximal tibia. Furthermore, inclusion of changes in JRFs and lower limb alignment improved model fit significantly. Results suggest that individuals with high preoperative BMD and large reductions in joint loading post-operation are at the highest risk for bone loss around the tibial component following a primary TKA.
In summary, the collection of studies presented in this thesis provide new insight into factors related to bone remodelling following a primary TKA. Bone remodelling occurring primarily near the implant may be clinically relevant with respect to implant loosening and is related to preoperative BMD and knee joint loading. Further research is needed to determine clinically significant estimates of BMD loss as it relates to aseptic loosening. However, assessing preoperative bone density prior to surgery and minimizing reductions in joint loading postoperatively may be valuable to improving longevity of a primary TKA.
Keywords: bone remodelling, bone mineral density, BMD, proximal tibia, total knee arthroplasty, knee joint reaction forces, musculoskeletal modelling
Subject: Medicine thesis
Thesis type: Doctor of Philosophy
Completed: 2025
School: College of Science and Engineering
Supervisor: Mark Taylor